Kido R, et al. - In this prospective cohort study of 5,515 adult hemodialysis patients, researchers examined how cardiovascular-comorbid condition affects the association between hemoglobin concentration and mortality. Over a median 2.0 years, they observed the occurrence of 847 all-cause and 326 cardiovascular deaths, and 1,000 adverse cardiovascular events. Haemodialysis patients with and without cardiovascular comorbidity differed in the association of low hemoglobin concentration with all-cause mortality. They observed higher relative mortality risk in correlation with low hemoglobin concentrations (< 10.0 g/dL) in non-cardiovascular-comorbid (CV−) patients vs cardiovascular-comorbid (CV+) patients, with higher thresholds of hemoglobin concentration for increasing mortality. They observed increasing mortality or risk of adverse cardiovascular events in correlation with higher hemoglobin concentrations, ranging from moderate anaemia to normal (≥ 11.0 to 11.9 g/dL), significantly so in CV− patients. These findings suggest a higher sensitivity to the detrimental effect of low hemoglobin concentration among CV− patients vs CV+ patients.